There will also be no checks or controls on the Irish border, according to the plan.

It says the plan recognises the unique circumstances of Northern Ireland.

It is possible that while Irish products would enter Northern Ireland tariff free, products moving in the other direction would face tariffs.

Image copyrightAFPImage caption The prime minister lost a second vote on her withdrawal deal in Parliament by 149 votes on Tuesday evening

The government said it recognises that Northern Ireland’s businesses and farmers will have concerns about the impact that the government’s approach will have on their competitiveness.

It stated: “These are the only steps the UK government can unilaterally take to deliver on our absolute commitment to avoid a hard border in the event of no deal.”

It added that there will be no checks or controls on goods moving from Ireland to NI.

The government is also understood to be confident that the arrangement will not conflict with World Trade Organization rules.

Typically the WTO expects all members to be treated equally. So if zero tariffs are applied to one member they should be applied to all members.

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The special arrangement for Northern Ireland would appear to conflict with that.

It is understood the government could invoke an exemption to that non-discrimination principle.

‘Strictly temporary’

The government said the measures would be “strictly temporary” and that its priority would be to enter into discussions urgently with the European Commission and the Irish government to jointly agree long-term measures to avoid a hard border.

It said it would only apply a small number of measures necessary to comply with international legal obligations, protect the biosecurity of the island of Ireland, or to avoid the highest risks to Northern Ireland businesses – which will not require land border checks.

It is understood the government acknowledges there will be a risk of Irish smugglers using Northern Ireland as a backdoor to get goods into GB tariff free.

They intend to tackle this with an ‘anti avoidance rule’ which will be enforced on the basis of intelligence.

There is no plan to have routine checks or controls on Northern Ireland goods crossing the Irish Sea.

Analysis: John Campbell, NI economics & business editor

What is being proposed here is quite extraordinary.

You would have a scenario in which, if you’re a food exporter in the Republic of Ireland and send goods to Holyhead, you will face tariffs. If you send it over the border to Newry, you will not face tariffs.

Image copyrightGetty ImagesImage caption Under the plan, food producers in the Republic of Ireland would not face tariffs for sending their produce to Northern Ireland

However, you could have the situation in which farmers and food producers in Northern Ireland trying to send their stuff in the other direction will face tariffs.

That will be up to the Irish government and the EU to decide.

So it will seriously undermine the competiveness of Northern Ireland farmers.

It said that to prevent unfair treatment of Northern Ireland businesses, goods arriving from the Republic of Ireland would still be subject to the same VAT and excise duty, and the UK government would continue to collect these taxes on Irish goods in future.

Secretary of State Karen Bradley said: “The government has been clear that a deal with the European Union is the best outcome for Northern Ireland.

“But we will do all we can to support people and businesses across Northern Ireland in the event that we leave without a deal.